<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
</head>

<body>

</body>
<script>
    var arr = ['user', 'user', 'user', 'admin'];
    var res = arr.some(function(v, i, origin) {
        return origin[i] === 'admin'
    }, this);
    console.log(arr); //["user", "user", "user", "admin"]
    console.log(res); //true
</script>

</html>